CHI98LA128

While at cruise altitude, the pilot said he noticed a burning smell after he had operated the experimental airplane's auxiliary fuel pump. He said he did not notice any changes in the engine indications. He said, 'Approximately 1-minute later I noticed the reduction in engine power... .' He said he decided to make a precautionary landing on a road. When the pilot reduced the engine's power setting, the engine experienced a total loss of power. The pilot said the airplane '...built up excessive speed...' during its descent. During the landing, the airplane encountered ground affect and did not touch down as the pilot had intended. While in ground affect the airplane collided with a telephone pole and bridge frame before colliding with a ditch and coming to rest. The on-scene investigation revealed that the airplane's engine driven magneto experienced a drive coupling failure. The coupling had fractured into 4 pieces. One face on two of the four pieces had a surface with beach marks on them and no shear lips along their edges. These two faces matched each other. The remaining fracture surfaces had a coarse texture with shear lips along their edges.

On April 17, 1998, at 1730 eastern standard time (est), a R.G. Jaeger Sonerai II- L, N247RJ, piloted by a private pilot, was destroyed during a collision with a telephone pole, bridge guard rail and terrain while making a forced landing following a total loss of power while in cruise flight. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 personal flight was not operating on a flight plan. The flight departed Junction City, Kentucky, at 1500 est.

According to the pilot, while at cruise altitude, he noticed a "...burning smell... ." He said there was no smoke present and the engine gauges were "...normal." He said he had planned on landing at an alternate airport, but was forced into doing an off airport landing because the engine began to lose power.

The pilot said he "...elected to land on..." on a long rural road that he thought was free of obstructions. He said, "When I pulled the power back the engine stopped. As I descended to the road I built up excessive speed... ." He said the airplane's excessive speed had to be bled off before the airplane would touch down. During the deceleration process, the airplane collided with the telephone pole and bridge frame before colliding with a ditch and coming to rest.

The on-scene investigation was conducted by a Federal Aviation Administration (FAA) Principal Maintenance Inspector (PMI). According to the PMI, N247RJ's engine had a fractured magneto drive coupling that had forced the magneto to stop functioning. The magneto drive coupling was made from cast aluminum. The casting had broken into four irregularly-sized pieces. One part of the casting had melted and was fused to the engine mount. The coupling had fractured at the key ways. Except for 2 fracture surfaces, the surfaces of the fractured pieces were grainy in appearance and had shear lips along their edges. Both of these surfaces had a texture that appeared smaller than the texture of the other pieces. These surfaces had beach marks and did not have shear lips along its edge.

According to the pilot-owner, the drive coupling s manufacturer is unknown. It was purchased from the airplane kit manufacturer. The kit manufacturer is no longer in business. The pilot-owner said the design of the coupling has been changed two times since the cast aluminum unit was manufacturered. The FAA POI submitted a Malfunction or Defect Report on the failed coupling.